1. Field of the Invention
The application relates generally to the field of street drainage, more specifically to drain grates that are movable in response to water flow therethrough.
2. Description of the Related Art
Road drainage systems such as curb-integrated storm drains are common throughout urban and suburban areas. In these areas, litter, trash, and other debris such as plant trimmings, leaves, and bark may accumulate on the roadway and be blown or washed towards the drains. In dry seasons, when the precipitation is not sufficient to flush the drain systems regularly, the debris may accumulate in the drains.
In a subsequent rainy season, the accumulated debris may clog the drain, leading to greatly reduced drain capacity and ultimately road flooding at or near the drain opening. Additionally, the flow of water through a drain that is clogged or partially clogged with debris is likely to result in the release of some or all of the debris into the flow of water continuing downstream from the drain. Often this trash, plant material, and other debris flows into oceans, creeks, rivers, and streams. To reduce the incidence of flooding, municipalities often expend considerable resources and employee time cleaning accumulated debris out of drains and drain basins to reduce the risks of roadway flooding and pollution.
Drain grates, positioned at or in a drain opening, have been developed to block the entry of debris into the drain system. This allows the debris to be removed by a street sweeper or by other conventional roadway cleaning techniques. To block the entry of debris while maintaining optimum drainage capacity, the grate should be removable from the drain opening when the flow of water through the drain reaches and exceeds a predetermined rate.
In dry and low water flow situations, the drain grate would remain closed in the drain opening, permitting passage of water through the grate, but blocking debris too large to fit through the grate. In higher water flow situations, an actuator connected to the drain grate would cause the drain grate to move away from the drain opening, thus increasing the flow capacity through the drain. The actuator of these systems typically comprised a container having a drain opening. These movable drain grates, while desirably preventing debris accumulation during relatively dry weather and allowing higher flow capacity during high water flow periods, remain prone to flooding in certain high water flow periods. In certain instances, enough water accumulates in the basin portion of the drain that the actuator floats in the accumulated water. Since the actuator is operatively connected to the drain grate, the flotation of the actuator closes the drain grate, thereby reducing the flow capacity of the drain opening. Thus, flow through the drain is reduced during instances (high water flow) when increased flow capacity is most desired.
Furthermore, some of the attempted solutions require a relatively deep basin to operate effectively. The depth of a roadway drain can be dependent on its distance from a drainage system outlet such as a stream, river, lake, or ocean, such that the drainage system floor has a slope to provide gravity feed from all of the individual drains to the endpoint without pooling. Thus, actuators in some of the previous drain grate actuation systems could not be sized to fit a relatively shallow drain basin. Additionally, various cities and counties have drafted rules and regulations limiting the size of acceptable drain grate systems such that many of the previous designs are no longer acceptable.
In light of the shortcomings of the prior art noted above, there is a need for a drain grate system that prevents the accumulation of debris in the drainage system during dry weather, that opens the grate for increased capacity in response to relatively high water flow conditions, such as a storm water event, that remains open despite water accumulation in the drain, and that meets the needs of various city and county regulations.